One of the most harrowing images of the recent flooding in Louisiana showed the rescue of a woman and her dog from a car being swept away by fast-rising flood waters. The dramatic footage was captured by a local television crew.

Others have not been so lucky. Several counties in this southern US state have been battered by torrential rain. According to news reports, at least five people have died and over 20,000 have had to be rescued from homes that have all but disappeared under flood water.

Flood waters in Louisiana.

Image: REUTERS

On 12 August, Louisiana Governor John Bel Edwards declared a state of emergency for the entire state of Louisiana as a result of the severe weather.

US natural disasters

The flooding is unprecedented, but it’s not the first time that this area has been hit by severe weather. In 2005, the region suffered one of the worst natural disasters in US history, when Hurricane Katrina hit the gulf coast.

The storm killed nearly 2,000 people and displaced 1 million. Thousands of homes were flooded and destroyed, and an estimated 80% of New Orleans was under water, up to 20 feet deep in places.

Victims of Hurricane Katrina seek shelter.

Image: REUTERS/Carlos Barria

Seven years later, in 2012, Hurricane Sandy blew in over New York, becoming the state’s worst natural disaster. It killed 44 people and caused severe damage to roads, sewer systems and communications networks.

A home destroyed by Hurricane Sandy.

Image: REUTERS/Eric Thayer

But not all disasters are so dramatic. Severe heatwaves have killed more people in the US than any of the wind or rain-based weather events of the past 30 years – that’s despite there being much less in the way of actual damage. For instance, in 1980 a severe heatwave hit the Midwest, killing hundreds, affecting agriculture, and putting massive strain on the local power grid as the use of air conditioning units boomed.

In 1988, another heatwave, known as the North American Drought, was more widespread and was the costliest disaster prior to hurricane Katrina.

Image: NOAA

Hot and dry conditions are also behind the wildfires currently sweeping through California, which have forced thousands to evacuate their homes. Global warming is a major contributor to wildfires, as well as to other severe weather events. As temperatures rise, and drought spreads, the perfect conditions are created for fire to take hold. That said, the overwhelming majority of wildfires that occur in the US are actually started by humans. As the population grows, so the risks intensify.

The costs of natural disaster

While the cost of a natural disaster can be high in human terms, the financial costs are enormous.

Hurricane Katrina is the costliest hurricane ever in US history, coming in at $108 billion, with $81 billion of that in property damage. The heatwave of 1980 cost $29 billion and over 1,000 lives.

Worldwide, natural disasters caused a total of $1.5 trillion in damage between 2003 and 2013. And costs are rising. The UN Special Representative for Disaster Risk Reduction, Robert Glasser, warned recently that without investing significantly more in disaster reduction – such as in infrastructure, storm shelters and early warning systems – the situation will only get worse.